Classified

ABSTRACT

A munition includes a winding the configuration of which is changed as the munition detonates. The coil is seeded with a current and as the configuration of the winding changes a large em pulse is generated. Detection of the pulse can indicate whether or not the explosion is satisfactory and that the target is this destroyed. This avoids having to unnecessarily attack the target again.

This invention relates to apparatus and a method for determining theoperation of a munition and is particularly, but not exclusively,applicable to a munition designed to explode in a position where it isobscured from view.

Airpower is widely recognised as a significant factor in modern warfare.Recent conflicts such as the Gulf war and Kosovo have utilised airpowerto a very significant extent. Modern anti-aircraft weapons however causepilots to attack targets from a high or very low altitude in order toavoid being shot down. A consequence of this is that very many moretargets are reported as destroyed than are actually destroyed. Whilstrecognisance satellites and aircraft can later confirm whether or notthe target has been destroyed this is not always possible. A type oftarget that poses particular difficulty is that of the hardenedunderground bunker. These are particularly important targets for thefollowing reasons.

Hardened bunkers are used to house important assets such as command andcontrol infrastructure or chemical or other weaponry. The effortrequired to construct such bunkers shows the importance of theircontents. By successfully destroying the contents of the bunker theeffects are much more significant than for example destroying onearmoured vehicle. Accordingly, significant effort is required to mount amission to attack such a target. It is important to note that themission will involve not just one aircraft dropping a bunker-destroyingbomb. The mission will require a host of other aircraft from re-fuellingtankers, electronic countermeasure and defence system suppressionaircraft and air defence fighters. In essence a single attack mayinvolve the use of dozens of people and military assets and expose anumber of personnel to possible harm. Each attack is therefore asignificant undertaking and it is very important to be able to determinethe success of the attack.

In the Gulf war a rather crude way of determining the success of abunker attack involved the attacking aircraft aircrew monitoring for thesight of a secondary explosion. A secondary explosion is caused by thecontents of the bunker being caused to explode by the explosion of theaircraft's munition. This approach is unsatisfactory. Firstly, it ispossible for the contents of a bunker to be destroyed but for there tobe no secondary explosion. For example, a bunker housing communicationsequipment may not give rise to a perceivable secondary explosion.Secondly, a bunker will have many metres of reinforced concrete whichmay to a significant extent contain the secondary explosion. Of course,the bunker may also be empty. The unfortunate consequence of this isthat the mission may be re-planned and carried out again when there isno need to do so.

A further problem is the use of countermeasures to fool attackingaircraft that the mission has been successful by for example causing adecoy secondary explosion or by simulating damage to be viewed by laterreconnaissance.

It is an object of the invention to provide an apparatus and a methodwhich alleviates these problems.

According to the invention there is provided in a first aspect apparatusas set forth in claim 1 and in a second aspect a method as set forth inclaim 15.

A specific embodiment of the invention will now be described, by way ofexample only, with reference to the drawings in which:

FIGS. 1 and 2 show a weapons system in accordance with the inventionbeing used to attack a hardened bunker;

FIG. 3 shows the weapons system of FIGS. 1 and 2 in block diagram form;and

FIG. 4 shows a munition used in the weapons system its operation.

With reference to FIG. 1, a weapons system 1 used to attack a hardenedbunker 2 comprises a launching platform in this case an aircraft 3,munitions 4, 5 and a management system 6 mounted on the aircraft whichincludes an antenna 7. The munitions will be described in greater detaillater but they use a combination of ballistic energy and a firstpenetrating charge to propel a secondary charge into the bunker cavity7.

The bunker itself is formed of layers of steel mesh reinforced concrete8. Each layer will have a different constitution to resist penetration.The thickness of these layers will be a number of metres. The bunkercavity 7 holds munitions 9 and personnel 10 and the bunker is primarilylocated below the ground surface 11.

FIG. 2 shows the bunker moments after impact which shows that themunition has entered the bunker cavity 7 having penetrated the layers ofconcrete 8 but just prior to detonation of the second charge.

Having now described the overall system and, in a broad way, the mannerin which it is used to attack a target, a more detailed description ofthe weapons system will be given by reference to FIG. 3. The weaponssystem has two major components. A first of these is the aircraft bornemanagement system 6 and the second being the munition borne components12.

The management system comprises the antenna 7 operably coupled to areceiver section 13. The receiver section is in turn coupled to aprocessor 14 and the processor to a targeting system 15. The targetingsystem is operated by the pilot of the aircraft 3 to allocate and directmunitions to targets. The way in which the system directs munitions tothe target may be by an optical fibre link, a laser illuminator, radiolink or by other means or a combination of these. The antenna andreceiver are configured to receive and analyses an electromagnetic pulseproduced by the munition as it detonates. The manner in which this pulseis produced will be described in detail later.

The munition borne components have a first set associated with a primarycharge on the munition which is used to penetrate the secondary chargeinto the bunker. It comprises a processor 16 operably coupled to a fusesensor 17, a detonator driver 18 under the control of the processor todrive an electrically activated detonator 19. The fuse sensor 17registers the impact of the munition on the outer layer of the bunker 2and the sensed output is passed to the processor 16. If the sensedimpact indicates a hard structure the driver is activated and thedetonator 19 triggered to explode the primary charge. If the impact isbelow a threshold the processor may determine that the impact indicatesa softer layer which may be penetrated using the munitions ballisticenergy. Upon hitting a harder layer the threshold may be crossed and thedetonator triggered.

The triggering of the primary charge then forces the secondary chargedown through the layers to penetrate into the bunker cavity 7. Thesecondary system then comes into play. The secondary system comprises afuse sensor 20 operably coupled to a processor 21. The processor 21 isin turn coupled to a coil driver 22. The coil driver is coupled in turnto a coil 23 which will be described a greater detail later. Theprocessor 21 is also coupled to a detonator driver 24 which is in turnused to trigger a detonator 25 to set off the secondary charge.

The fuse sensor 20 registers the penetration of the layers as a seriesof decelerations. The processor 21 monitors the output of the sensor todetermine the appropriate time to trigger the secondary charge. This maybe determined according to information known about the composition ofthe target. In this specific embodiment the charge is triggered after ithas entered the cavity but for other targets it may be triggered withinthe target layers. The triggering is caused by detecting no furtherdecelerations within a certain time frame. This will occur once themunition has entered the free space of the cavity 7. The processor 21firstly energises the coil 23 via the driver 22 and then the detonator25 via the driver 24 to initiate the secondary charge.

The configuration of the coil, its function and relationship with thesecondary charge and its interaction with the rest of the weapons systemto register a successful explosion will now be described with referenceto FIG. 4.

FIG. 4 a to 4 c shows the secondary charge in a sequence in themilliseconds following detonation. Accordingly, the reference numeralswill signify the same component through the figures. The secondarycharge 26 is generally cylindrical in configuration with the figuresshowing a longitudinal section. It includes an axially extending core ofhigh explosive 27 such as C4. At one end of the explosive core 27 islocated a detonator and a shaped charge or explosive lens used toproduce when initiated a plane explosive shock wave which travels leftto right in the explosive core to cause detonation. (The progression ofthe explosive event is shown in the FIGS. 4 b and c.) The explosive coreis located within a copper armature tube 29 the purpose of which will belater described. A cylindrical stator winding 30 of copper wire islocated to be coaxial with the armature tube. and spaced apart. Thewinding 30 is supported by a cylindrical dielectric jacket 31 whichprevents adjacent turns of the winding 30 from contacting each other.The coil 30 is provided with a stator-input ring 32 and a stator outputring 33. These are connected to the coil and are held apart from thearmature tube 29 by annular insulator blocks 34 and 35. It should benoted that the inwardly directed surface of the winding 30 and theoutwardly directed surface of the armature tube 29 are held in spacedapart relationship but the space therebetween is empty apart from thesupporting insulating blocks 34.

During the initiation phase when the secondary charge is determined ashaving entered the bunker cavity 7 a seed current is set up in thestator winding 30 (the coil 23 referred to in FIG. 3) and the explosivelens initiated (the detonator 25 of FIG. 25). This initiates theexplosive core 27 and a detonation wave progresses left to right in thefigure. This causes a rapid expansion of the copper tube 29 radiallyoutwards in the manner shown in FIGS. 4 b and c. This causes aprogressive although exceedingly rapid bringing into contact of the tube29 and the windings 30. The tube 29 shorts adjacent windings causing theseed current to be progressively compressed into the remaining coilsamplifying the resultant magnetic field many times over. The more rapidthis expansion is the higher frequency component the resultant magneticfield. Accordingly, a resultant electromagnetic pulse is produced whichmay be detected and used to determine how much of the explosive core 27has detonated. A pulse of high energy will indicate a complete explosionwhereas a lower energy pulse will indicate that the core has notdetonated explosively but has rather burnt. Levels in between willindicate partial explosion.

The antenna 7 of the aircraft 3 will detect the pulse and pass theresult interpreted by the receiver 13 and the processor 14 to thetargeting system 15. In the event that the pulse does not meet thepredetermined criteria for a successful attack, the targeting systemalerts the pilot (or other systems such as a recording system). In thisembodiment the targeting system allocates the other dropped munition 4to this bunker target.

In the event that the pulse meets the criterion for a successful attack,the munition 4 is reallocated to another target and directedaccordingly. The success of the attack is notified to the pilot and alsorecorded for later post mission analysis.

It is may be also possible to modulate the resultant impulse orimpulses, to indicate other parameters of the mission, such as thenumber of voids counted.

1. Apparatus for producing an indication of the detonation of a munitioncomprising a winding for, in use, carrying a current which winding beingarranged to change configuration by the detonation of the munition thuscausing a variation in the field produced by the current and to producethereby the indication, wherein at least one resultant impulse ismodulated to indicate at least one other mission parameter.
 2. Apparatusas claimed in claim 1 wherein the configuration of the winding is one inwhich the number of electrically distinct windings is varied. 3.Apparatus as claimed in claim 2 wherein windings are shorted to changethe configuration.
 4. Apparatus as claimed in claim 3 wherein anarmature is driven into contact with the winding by the detonation ofthe munition to change the configuration of the winding by shorting atleast some of the windings.
 5. Apparatus as claimed in claim 4 whereinthe armature is arranged about an explosive core to be driven therebyinto contact with the winding.
 6. Apparatus as claimed in claim 5wherein the winding, a stator and the explosive are co-axial. 7.Apparatus as claimed in claim 6 wherein the armature and the winding aremaintained apart at least in part by an electrically insulting material.8. Apparatus as claimed in claim 1 comprising a detector for detectingthe occurrence of an electromagnetic pules produced in use by thewinding.
 9. Apparatus as claimed in claim 8 wherein the detectordetermines the occurrence of satisfactory detonation of the munition byreference to the characteristics of the pulse.
 10. Apparatus as claimedin claim 9 wherein the characteristics include magnitude.
 11. Apparatusas claimed in claim 8 wherein the detector is located at an aircraft.12. (canceled)
 13. A munition including apparatus as claimed in any oneof claims 1 to
 7. 14. An aircraft including apparatus as claimed inclaim
 1. 15. A method for producing an indication of the detonation of amunition comprising providing a winding the configuration of which isvaried by detonation of the munition; providing a current in the windingand detecting an electromagnetic pulse produced by the winding as itsconfiguration varies; and modulating at least one resultant impulse toindicate at least one other mission parameter.
 16. A method as claimedin claim 15 wherein a characteristic of the pulse is used to determinewhere a detonation criterion has been met.
 17. A method as claimed inclaim 16 wherein the characteristic includes the magnitude of the pulse.18. (canceled)